Regulated progression of B lymphocyte differentiation from cultured fetal liver.

Lymphoid fetal liver cultures (LFLC) are long-term, nontransformed cultures of early B lymphoid lineage cells which appear developmentally blocked at the pre-B stage in vitro. When injected into severe combined immunodeficient (SCID) mice, cells from LFLC could reconstitute splenic B lymphocytes and serum IgM. T lymphocyte reconstitution was not observed and serum IgG levels were very low. IgG3 was the predominant gamma subisotype in the serum of the LFLC-reconstituted mice, indicating impaired class switching in these B lymphocytes. When thymocytes were coinjected with LFLC, the B lymphocytes were able to class switch fully and respond to T-dependent antigens. These serological responses were heterogeneous. This experimental system allows separation of three B lymphocyte developmental stages: early differentiation in vitro, progression to IgM secretion in vivo, and late differentiation dependent upon mature T lymphocytes in vivo. The unique advantage of this system is the ability to regulate the B lymphocyte developmental pathway in a defined, stepwise manner

Long-term cultures of murine fetal liver retain very early B lymphoid phenotype.

Long-term cultures of murine fetal liver have been successfully established using a modification of our in vitro bone marrow culture system (14, 15). Fetal liver cells from midgestation BALB/c embryos were plated onto BAB-14 bone marrow stromal cell-adherent layers. After a 3-5 wk period, cell growth began to increase and these cells were expanded in number on fresh feeder layers. The cultured fetal liver cells were lymphoid in morphology, 5-20% cytoplasmic Ig-positive, but less than 1% surface Ig-positive. Southern blot analysis of the cultured fetal liver cells, as well as cultured bone marrow-derived B cells, demonstrated a population with germline Ig heavy chain loci, possibly representing very early B cell precursors. Abelson murine leukemia virus (A-MuLV) clonal transformants of such cultured fetal liver cells had a phenotypic distribution similar to that seen with fresh fetal liver transformants but distinct from those obtained with the transformation of either cultured or fresh bone marrow. All A-MuLV transformants isolated had rearrangements at the mu heavy chain locus of both chromosomes, irrespective of Ig production. In addition, most mu heavy chain producers had at least one rearranged kappa gene locus. These long-term fetal liver cultures provide large numbers of cells for studying events early in the B lymphocyte lineage. The cultured fetal liver cells retained phenotypic traits similar to fresh fetal liver B cells and distinctive from bone marrow cells cultured under similar conditions

Assessment of food safety practices among cassava processors in selected rural communities of Oyo State, Nigeria

Food safety assessment is an effective means of discovering knowledge and data gaps that limit effective risk analysis and at the same time providing information to develop public policies on food safety management. The study assessed the cassava food safety practices among cassava processors in selected rural communities of Oyo State. Both qualitative and quantitative research designs were used to examine the following parameters: knowledge, attitude, sources of information and constraints to food safety practices. Focus Group Discussion, In-depth Interview, direct observation and interview schedule were the sources of primary data used. Multi-stage sampling technique was used to select one hundred and fifty-four (154) men and women involved in cassava processing from four Local Government Areas where there is concentration of cassava production and processing activities in the state, namely: Saki-West, Saki-East, Atisbo and Afijio. Data were analyzed using percentage, mean, Analysis of Variance and Chi square. The findings revealed that the mean income was N20,695, majority of the processors have low knowledge (71.4%) and unfavourable attitude (51.3%) towards cassava safety practices. Public sanitary officers (x̅ = 2.61) and fellow processors (x̅ = 2.11) were ranked as the most used sources of information about cassava safety practices. Constraints to food safety practices include: processing is time consuming, the cumbersome nature of the safety practices and inadequate access to clean water. Inferential analysis of results shows that income contributed significantly to the cassava food safety practices (p = 0.04) and safety practices do significantly differ among cassava processors across the selected cassava processors (p = 0.10). However, no significant relationship between sex (p = 0.42), age (p = 0.48), marital status (p = 0.67), educational level (p =0.53), processing experience (p = 0.92) and safety practices of the respondents. Training and effective monitoring by relevant stakeholders will further boost processors’ knowledge and attitudinal change towards food safety and ultimately safe food for the consumers.Keywords: Assessment, Food, Safety, Practices, Processors, Cassava, Rural, Communit

Meta-analysis guided development of a standard artificial urine

\ua9 2024 The AuthorsIn this study, we present the first meta-analysis of human urine reported in the literature, drawing data from a total of 35 articles with a combined participant count of 14,021. Through this analysis, we have developed an artificial urine (AU) composition that can be adjusted within typical physiological parameters for in vitro applications. Our findings demonstrate the utility of this AU in determining the solubility of nitrofurantoin, particularly in the context of crystalluria. Notably, we observe that in saline, nitrofurantoin solubility, within the framework of its urinary pharmacokinetics, suggests a risk of crystalluria. However, in AU, this risk is mitigated due to complexation with urea. More broadly, we anticipate that our developed formulation will serve as a foundation for translational studies across biomedical and pharmaceutical sciences

ENVIRONMENTAL EFFECTS ON BACTERIAL COMMUNICATION AND COMMUNAL BEHAVIOR

Despite their autonomous nature, bacteria can often reside within complex, multicellular communities. One benefit of communal organization is the protection it offers from hazardous environments around the cells, which can come in the form of physical shielding or collective adaptive behaviors that arise from cell aggregation. This dissertation explores how environmental conditions itself might modulate or trigger these collective cell behaviors. We first explored how the environment can affect the active coordination of collective cell behavior, which involves cell-to-cell communication mechanisms such as quorum sensing (QS). Using a microfluidic platform to modulate the environment, we showed that existing explanations of environmental dependence pertaining to modulation of signal retention alone were inadequate in explaining the response. Instead, a dynamics-based analysis coupled with a mathematical model revealed a regulatory mechanism that is defined by the growth-mediated balance between synthesis and dilution of the signaling machinery proteins. This mechanism is able to account for the temporal and spatial properties observed during the onset and propagation of the collective response. These properties culminated in a cell education strategy that effectively combines response diversification with cell signaling to accelerate the onset of the collective cell behavior, which can have tremendous implications for the fitness of the cells that can exhibit this behavior. In addition, we also examined the effects of direct environmental cues, such as mechanical cues, on the emergence of collective cell behaviors. We found that physical confinement of bacterial colonies can lead to a buildup of self-imposed mechanical stress, which can elicit a biological stress response and the secretion of biofilm-related extracellular materials. We demonstrate that this renders the colony biofilm-like, with the associated functional consequence of increased antibiotic tolerance. Across these studies, we combined engineering approaches with experimentation and computational modeling to explore the relationship between bacterial colonies and its surrounding environment and found a high degree of dependence, most often reflected in spatial dependences of responses. As the appreciation for the importance of the microenvironment and its influence on bacterial colonies grow, we anticipate that the interdisciplinary approaches presented here will prove to be valuable tools in helping us understand the workings of bacterial collective cell behavior

The Fee Sensitive Risk Exposures of Project Authorized Person in Hong Kong

Authorized Persons (AP) play a critical role in the design and construction of building works in Hong Kong. Under the Building Ordinance, design and construction of building works need to be coordinated and monitored by an AP registered with the Buildings Department. Professionally qualified Architects, Engineers and Surveyors are eligible to register as AP after completing the prescribed assessment. In addition, the project AP is often appointed by the project owner to be the project team leader. In these capacities, a project AP is exposed to various risks. This paper seeks to identify the fee sensitive risk exposures of project APs. Through an ANOVA study, these risks exposures are those due to liabilities under the Building Ordinance at the construction stage, those towards the third parties and the clients

The lift industry in Hong Kong : regulatory action and capacity building

published_or_final_versionPolitics and Public AdministrationMasterMaster of Public Administratio

Return migration and re-migration of Brazilian-Japanese and the role of identity in their migration

published_or_final_versionInternational and Public AffairsMasterMaster of International and Public Affair